Billions of years before the first nucleated cell drew breath, ancient cyanobacteria had already solved one of life's deepest coordination problems: how to make cells speak to one another. Researchers at Heinrich Heine University Düsseldorf have found that these prokaryotic ancestors used calcium-regulated junction structures functionally identical to those governing the human heartbeat and neural thought, suggesting that the molecular grammar of multicellular life was written far earlier than science had imagined. The discovery does not change how we understand our own biology so much as it h
Ancient bacteria used calcium-based cell communication like modern humans
Calcium signaling is ancient—older than complex life itself.
Mark
So bacteria were doing this a billion years ago? That seems like a very long time to keep the same system.
Mimi
It does, and that's the point. If it worked then, and it still works now, there's probably a reason. Calcium signaling is elegant and efficient. Once evolution found it, there was no need to throw it away.
Luke
But I want to be careful here. The researchers found similar structures and similar proteins. Are we certain the mechanism is identical, or just analogous?
Mimi
That's fair. They showed the protein binds calcium and regulates the junctions. The function appears to be the same. But you're right that "similar" and "identical" are different claims.
Mark
What does this mean for understanding how complex life evolved?
Mimi
It suggests that multicellular coordination didn't have to be invented from scratch when eukaryotes appeared. The toolkit was already there. Bacteria had already solved the problem of how to make cells work together.
Luke
Though we should note—these are multicellular cyanobacteria, not single-celled bacteria. They were already organized. So the question of how that organization first arose is still open.
Mark
Right. So this pushes back one mystery but doesn't solve the earlier one.
Mimi
Exactly. But it does tell us that tissue-like organization and calcium-based communication are very old strategies in life.
Luke
And the CSE protein—is it found in any eukaryotes, or is it unique to these bacteria?
Mimi
From what the paper describes, it appears to be unique to the multicellular cyanobacteria. Which is interesting in itself.
Mark
Why would that be?
Mimi
Possibly because eukaryotes evolved different calcium-binding proteins that do similar work. Evolution often finds multiple solutions to the same problem.
Der Puls
- The assumption that sophisticated cell-to-cell communication belonged exclusively to complex, nucleated life has been quietly overturned by bacteria that predate those cells by a billion years.
- At stake is the entire timeline of biological coordination: calcium signaling — the mechanism behind heartbeats, nerve impulses, and tissue cohesion — must now be understood as a prokaryotic invention, not a eukaryotic one.
- Using nuclear magnetic resonance spectroscopy and cryo-electron microscopy, the research team mapped a calcium-binding protein unique to multicellular cyanobacteria, demonstrating it actively regulates the very junctions that connect neighboring cells.
- When mutant bacteria were stripped of this protein, their connecting structures collapsed — confirming that calcium regulation was not a coincidental feature but the architectural foundation of bacterial multicellularity.
- The discovery pushes the evolutionary clock back by roughly a billion years, landing science at a new and unsettling threshold: the fundamental principles of complex life were already operational before complex life existed.
Billions of years before the first nucleated cell drew breath, ancient cyanobacteria had already solved one of life's deepest coordination problems: how to make cells speak to one another. Researchers at Heinrich Heine University Düsseldorf have found that these prokaryotic ancestors used calcium-regulated junction structures functionally identical to those governing the human heartbeat and neural thought, suggesting that the molecular grammar of multicellular life was written far earlier than science had imagined. The discovery does not change how we understand our own biology so much as it humbles our sense of its origins — revealing that what we call complexity may be, at its root, a very old conversation.
A team of biologists studying Earth's most ancient living organisms has found that bacteria billions of years old were already using the same chemical language that coordinates the human heartbeat and nervous system. Published in The EMBO Journal, the discovery suggests that calcium-based cell communication — long assumed to be an innovation of complex, nucleated life — actually originated in simple prokaryotic bacteria that formed tissue-like structures long before animals or plants existed.
In modern humans, cells coordinate through specialized connecting bridges, with calcium ions serving as the currency of that conversation. This mechanism was thought to have evolved only after cells developed nuclei and greater complexity. But researchers at Heinrich Heine University Düsseldorf, led by Junior Professor Khaled Selim, found something different when they examined multicellular cyanobacteria — among the earliest photosynthesizing organisms on Earth. These bacteria, which lack nuclei entirely, possessed structures functionally identical to the gap junctions that connect human cells, using them to pass signals between neighbors in the same way.
The team's surprise deepened when they identified a calcium-binding protein — abbreviated CSE — found exclusively in these multicellular cyanobacteria. Mapping its three-dimensional shape through nuclear magnetic resonance spectroscopy, they discovered it acted as a molecular buffer, holding and releasing calcium to regulate signal flow between cells. When cryo-electron microscopy was used to examine bacteria engineered without this protein, the connecting structures between cells were dramatically reduced — confirming that calcium regulation was not incidental but essential to building the bridges that made bacterial community possible.
Selim noted that finding these mechanisms in organisms so ancient and structurally simple implies the governing principles of multicellular coordination were already established before prokaryotes and eukaryotes diverged — an event itself roughly a billion years ago. The calcium-signaling architecture underlying human hearts, brains, and tissues does not merely resemble what these bacteria were doing; it descends from it. The discovery does not rewrite cellular biology, but it relocates its deepest roots to a world that existed long before complexity was supposed to have begun.
A team of biologists studying some of Earth's oldest living things has found something unexpected in their microscopes: bacteria billions of years old were already using the same chemical language that your heart uses to beat, that your nerves use to think. The discovery, published in The EMBO Journal, suggests that one of life's most fundamental tricks—cells talking to cells through calcium signals—did not originate in animals or plants at all, but in simple, ancient bacteria that formed tissue-like structures long before complex life existed.
In modern humans and animals, cells communicate through specialized connecting structures. Your heart muscle cells coordinate their contractions through these bridges. Your neurons fire signals across them. Your tissues hold together because of them. Scientists have long understood that calcium ions, those charged particles of the element calcium, are the currency of this conversation—when calcium flows between cells, information flows with it. But this mechanism was thought to be a relatively recent invention, something that evolved only after cells developed nuclei and became more complex.
The research group at Heinrich Heine University Düsseldorf, led by Junior Professor Khaled Selim and including collaborators from the University of Tübingen, was studying multicellular cyanobacteria—some of the earliest organisms to photosynthesize, dating back roughly a billion years or more. These bacteria lack nuclei, making them prokaryotes, simpler in almost every way than the cells that make up your body. Yet when the team examined how these ancient bacteria coordinated with one another, they found structures that looked functionally identical to the gap junctions that connect human cells. The bacteria called them septum junctions, and they served the same purpose: allowing cells to pass signals to their neighbors.
The surprise deepened when the researchers identified a calcium-binding protein, which they abbreviated as CSE, that existed only in these multicellular cyanobacteria. Using nuclear magnetic resonance spectroscopy, they mapped the precise three-dimensional shape of this protein when calcium was bound to it. The protein acted as a calcium buffer—a molecular container that could hold and release calcium ions, regulating the flow of signals between cells. When the team used cryo-electron microscopy to examine mutant bacteria that lacked this protein entirely, those cells had far fewer connecting structures. The calcium-regulation system was not incidental; it was essential to building the bridges between cells.
Selim reflected on the implications: finding these structures in organisms so ancient and so simple suggested that the basic principles governing how complex life coordinates itself were already established before the evolutionary split between prokaryotes and eukaryotes. That divergence happened roughly a billion years ago. The calcium-signaling system that allows your heart to pump, your brain to think, your tissues to hold their shape—all of it traces back to bacteria that were already using it when the first nucleated cells were still emerging. The discovery does not rewrite what we know about how your cells work, but it does push back the clock on when life figured out how to make it work at all.
Bemerkenswerte Zitate
It came as a big surprise to us that one of the earliest life forms on Earth had already developed communication structures regulated by calcium signals similar to those found in the cells of higher organisms.— Junior Professor Khaled Selim, Heinrich Heine University Düsseldorf
These cellular connections date back a billion years—before the time when the evolutionary lineages of eukaryotes and prokaryotes diverged.— Khaled Selim
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